The present invention relates generally to medical imaging and, more particularly, to a system and method of imaging a region of interest (ROI) based upon patient size and/or task selection, preferably in computed tomography systems.
Typically, in computed tomography (CT) imaging systems, an X-ray source emits a fan-shaped beam toward an object, such as a patient. The beam, after being attenuated by the patient, impinges upon an array of radiation detectors. The intensity of the attenuated beam radiation received at the detector array is typically dependent upon the attenuation of the X-ray beam by the patient. Each detector element of the detector array produces a separate electrical signal indicative of the attenuated beam received by each detector element. The electrical signals are transmitted to a data processing unit for analysis which ultimately results in the formation of an image.
Generally, the X-ray source and the detector array are rotated with a gantry within an imaging plane and around the patient. X-ray sources typically include X-ray tubes, which conduct a tube current and emit the X-ray beam at a focal point. X-ray detectors typically include a collimator for collimating X-ray beams received at the detector, a scintillator for converting X-rays to light energy adjacent the collimator, and photodiodes for receiving the light energy from the adjacent scintillator.
In one known CT imaging system used to image an ROI, imaging of a patient is conducted by moving the patient through a gantry. Preferably, it is desirable to minimize the patient""s exposure to X-rays. To do so, improved signal processing has allowed the use of lower dose CT scans, such as the commercially available 0.5 second CT scanner. However, for larger and heavier patients, low signal streaking problems are known to occur due to low tube current values for certain angular views. One proposed solution to the low signal streaking problem is to determine a threshold based upon clinical evaluation of large or heavy patient scans. The determined threshold is then fixed, and corrections during image processing are performed based upon a signal strength that corresponds to X-rays being attenuated by large or dense objects. Problems arise, however, when reducing the dose in CT scans further, and in particular, for smaller patients and task dependent scans.
There is a need for a system that can apply the lowest possible patient doses based on patient size, especially for pediatric patients, and/or based on a task to be performed. Setting fixed patient thresholds to correct for low signal streaking problems in medium and smaller size patients does not improve reconstructed images of the patients, but may expose such patients to unnecessary X-ray radiation. Furthermore, certain sub-regions of the ROI may require a lower image resolution, or alternatively, a particular task such as Cardiac Artery Calcification Scoring may require a lower image resolution as compared to Cardiac Artery imaging thereby permitting application of a lower patient dose of radiation.
Since lower radiation exposure is an on-going goal in X-ray and CT development, it would be desirable to have an imaging system capable of processing imaging data according to an automated selection of a patient size and/or task dependency to reduce a patient""s X-ray exposure during scanning of the patient.
The present invention provides a system capable of processing imaging data according to selection of a patient size and/or task dependency to reduce a patient""s X-ray exposure during scanning of the patient, and a method of processing imaging data that solves the aforementioned drawbacks.
A system and method of computer tomography imaging to reduce a patient""s X-ray exposure based upon patient size and/or task selection prior to scanning of the patient are provided. The system includes a high frequency electromagnetic energy projection source to project X-rays towards an object, such as a patient. A detector receives the high frequency energy attenuated by the patient, and a plurality of electrical interconnects is configured to transmit detector outputs to a data processing system. The system also includes a computer capable of receiving a task and patient size dependency selection input and determining a threshold level based on the received inputs to separate the detector outputs into a number of projection sets for further image processing to reconstruct an image.
In accordance with one aspect of the present invention, a method of processing imaging data for a radiation emitting medical device includes the steps of providing a task and patient size dependency selection and setting a first threshold level based on the task and patient size dependency selection. The method also includes the steps of acquiring imaging data and separating the imaging data into a plurality of projection sets based on the first threshold level. The method further includes the step of uniquely processing the imaging data of each projection set to reconstruct an image.
In accordance with another aspect of the invention, a computed tomography system is provided. This system includes a high frequency electromagnetic energy projection source to project high frequency energy towards an object and a detector to receive high frequency electromagnetic energy attenuated by the object. The detector produces outputs that are transmitted to a data processing system by a plurality of electrical interconnects. The system further includes a computer programmed to receive the detector outputs and a task and patient size selection input, and determine threshold levels based on the received task and patient size selection input. The computer is further programmed to separate the detector outputs into a plurality of projection sets based on the threshold levels, and reconstruct the separated plurality of projection sets to produce a visual image.
In accordance with yet another aspect of the invention, a computer-readable medium having stored thereon a computer program having a set of instructions that, when executed by a computer, will cause the computer to receive a selection signal of a task and patient size input, and determine at least one threshold based upon the received selection signal. The computer program also has instructions to receive imaging data signals acquired with low-dose radiation, and synthesize the imaging data signals into a plurality of projection sets. The computer further includes instructions to process each projection set based on the selection signal and the threshold, and to reconstruct a visual image with improved artifact reduction.
Various other features, objects and advantages of the present invention will be made apparent from the following detailed description and the drawings.